AVPlayer cannot remove a time observer that was added by a different instance of AVPlayer

AVPlayer 

An instance of AVPlayer cannot remove a time observer that was added by a different instance of AVPlayer.

解决办法

- (void)removeTimeObserver{    //[self.player removeTimeObserver:self.playbackTimeObserver];        @try{        [self.player removeTimeObserver:self.playbackTimeObserver];    }@catch(id anException){        //do nothing, obviously it wasn't attached because an exception was thrown    }}

问题 原因 重复释放  playbackTimeObserver